Pneumatic weft control means



Nov. 12, 196s 1 TE STRAKE 3,110,325

PNEUMATIC WEFT CONTROL MEANS Filed Jan. 25, 1961 United States Patent O'5,110,325 PNEUMAHC WEF? CQNTRQL BEANS Lambertus te Stralte, HuizeGallia, Deurne, Netherlands Filed Jan. 23, 255i, Ser. No. 34,0% 5Claims. (Cl. 139-127) This invention relates to loom apparatus ingeneral and in particular to a device for periodically drawing a loop ina thread by pulling the thread in through the open end of a hollow shafthaving a suction opening closable by a valve at the closed end. Thissuction opening is connected to a suction device, so that with thesuction valve open air enters the shaft at its open end and with thesuction valve closed the loop of thread can be readily rawn out of theshaft, without a suction Iaction being exerted on it. The shaft is animprovement on the shaft disclosed in U.S. Patent No. 3,024,8l4 issuedMarch 13, 1962, to Lambertus te Stralte, such patent showing thelocation and operation of the shaft in a weaving loom.

Suction of air into the hollow shaft on one side of the loom occursbetween the periods in which at the same side of the loom a weft threadis blown into the shed. The frequency of operation of this suctionaction for one hollow shaft is thus forced to be about periods perminute at a high worling velocity of the loom.

Because of the high frequency of operation the interruption of thesuction flow of the air into the hollow shaft has to occur as rapidly aspossible, so that the thread can be blown immediately into the shed andhence pulled out of the shaft. This means that the suction valve mustclose very rapidly to disconnect the suction line.

Flow interruption and the res ltant kinetic energy or" the air column inthe shaft by closure of the Valve causes very troublesome pressure waveformations. Due to the velocity of the air within the shaft, the airwill be a little compressed at the closed end of the shaft immediatelyafter the closing of the suction valve. Since the air is compressed itwill expand and air will flow back toward the open end of the shafttending to take the bottom of the U of the U-shaped loop of thread withit and entangling the thread.

lt is an object of this invention to provide improved loom apparatus. Itis a specific object of this invention to provide a loop drawing shaftas described herein wherein a rapid closure of a suction valve ispossible, thereby allowing operational speed of the loom to beincreased, while the consumption of air in the nozzles for the weftthread need not be higher than is necessary for a direct propulsion ofthe thread.

ri`he invention features a provision between the open end of a hollowshaft and Vthe suction opening at the closed end an air valve forincreasing the self-frequency of 'a pressure `wave occurring in theshaft as a result of closure of the valve of the suction opening. Thusthe air column cannot start resonating and if a resonance might arise, astrong attenuation or damping takes place as a result of the logarith ric decrease of the arising pressure wave.

lt is preferred that the distance between the air valve and the closedend of the shaft where the suction opening is provided, be such 'diatthe period of the pressure wave as a result of the closure of the valveis about 1A of the original period determined by the length of theshaft.

Other objects, features, and advantages will become apparent when thefollowing description is tarten in conjunction with the accompanyingdrawings, in which:

`FIG. l is a plan view of a shaft for drawing a loop in a length ofthread;

Patented Nov. l2, 1963 The shaft is disposed at the side of the loom,near the shed. A thread running along the open end l of the shaft isdrawn in a loop into the shaft when the thread is not under tension, asa result of the suction provided through a suction opening or apertureat the other end of the shaft 2.

The suction opening 2 can be closed by means of a valve 3. The opening Zis connected to a suction device via the conduit 4. rl'he shaft hasformed therein a at hollow recess or longitudinally extending threadreceiving slit 5 having a conduit or enlarged channel 6 along the edgeor periphery of the recess 5, said slit being of a width to readilyadmit said loop while preventing said loop from twisting.

The shaft housing comprises a lower half 7 and an upper half i8, thesehalves joined by suitable means such as threaded screw Preferably theupper half 8 of the housing is made of transparent material, so that theloop of the thread, when it is present in the shaft, is visible. This isdesirable when the loom is not in operation for the repair of a weavingfault, broken thread, etc.

As appears from FlG. 3, the cross-section of the shaft has the shape ofa dumb-bell or bar-bell, having two conduits or enlarged channels 6 atthe edges of the narrow slit 5.

In the 'lower half 7 of the housing there is formed a second aperture 9,access therethrough being controlled by a valve lil. Via thevalve-housing ll and the ports l2 the second aperture 9 is incommunication with the atmosphere when the valve l@ is open. The secondaperture 9 communicates with the thread receiving slit 5 intermediatethe opening of the slit from the shaft land the suction aperture 2.

During the suction of the loop in the thread into the recess 5 the valve3 is in the open position and the thread enters the shaft through theopening l in the shape or form of a loop. The substantially parallelthreads of the loop lie in the conduits or channels 6 because thesuction pull is stronger the channels.

At the moment that the thread is to be pulled out of the shaft the valve3 is closed and the suction action ceases.

At the same moment that the valve 3 is closed, the valve lil is opened,so that the edective length of the shaft in connection with or relativeto the resonance of the air column is suddenly interrupted. The valve`lil may also be opened a short period before closure of the valve 3.

'ln order to transmit the influence of the valve lt) with theappertaining second aperture 9 in the direction of propulsion of thepressure wave into the shaft, the second aperture 9 merges into anelongated longitudinal depression i3 formed in the lower half 7 andcommunicating with recess 5 where the second aperture 9 opens into therecess S formed inside the shaft.

By opening of `the valve l@ as described hereinbefore a correct dampingof the pressure wave occurring during closure of the valve 3 isobtained, avoiding undesirable secondary phenomena, causing the thread-to leave the position obtained when drawn into the shaft by suction andthus avoid entanglement thereof.

l claim:

l. A device for temporarily collecting a thread while preventingentanglement thereof comprising a shaft having formed therein alongitudinally extending thread receiving slit; said shaft also havingformed therein a suction aperture adapted to be utilized to lower `thepressure within said slit whereby a thread disposed adjacent said slitis drawn in a loop into said slit; said slit being of a width to readilyadmit said lloop while preventing said loop from twisting; first meansdisposed to control air ilow through said suction aperture; a secondaperture 3 formed in said shaft communicating with said threadreceivingslit intermediate the opening of said slit from said shaft and saidsuction aperture; and second means controlling air ilow through saidsecond aperture.

2. A device for temporarily collecting a thread while preventingentanglement thereof comprising -a shaft having formed therein alongitudinally extending thread receiving slit; said shaft also havingformed therein a suction aperture adapted to be utilized to lower thepressure within said slit whereby a thread disposed adjacent said slitis drawn in a loop into said slit; said slit being of a width to readilyadmit said loop while preventing said loop from twisting; first meansdisposed to control air flow through said suction aperture; a secondaperture formed in said shaft communicating with said thread-receivingslit intermediate the opening of said slit from said shaft and saidsuction aperture; and second means controlling air iiow through saidsecond aperture; said second means being operative to admit air ilowthrough said second aperture in response to ia cessation of flow throughsaid suction aperture.

3. A device for temporarily collecting a thread while preventingentanglement thereof comprising a shaft having formed therein alongitudinally extending thread receiving slit; said shaft also havingformed therein a suction aperture .adapted to be utilized to lower thepressure within said slit whereby a thread disposed adjacent said slitis dra-wn in a loop into said slit; said slit being of a width toreadily admit said loop While preventing said loop from twisting; meansdisposed to control air flow through said suction aperture; a secondaperture formed in said shaft communicating with said thread-receivingslit intermediate the opening of said slit from said shaft and saidsuction aperture; and means controlling air ow through said secondaperture; said second aperture merging with a longitudinal depressionformed in said housing and communicating with said thread-receivingslit.

4. A device for temporarily collecting a Athread while preventingentanglement thereof comprising a shaft having formed therein alongitudinally extending thread receiving slit; said shaft also havingformed therein a suction aperture adapted to be utilized to lower thepressure within said slit whereby a thread disposed adjacent said slitis drawn in a loop into said slit; said slit being of a width to readilyadmit said loop while preventing said loop from twisting; means disposedto control air ilow through said suction aperture; a second apertureformed in said shaft communicating with said thread-receiving slitintermediate the opening of said slit from said shaft and said suctionaperture; md means controlling air ilow through said second aperture;said second aperture being spaced from said suction aperture by`approximately onefourth of the distance between said suction apertureand the shaft opening of said threadeceiving slit.

5. A device for temporarily collecting a thread while preventingentanglement thereof comprising a shaft having formed therein alongitudindly extending thread receiving slit; said shaft :also havingformed therein a suction aperture adapted to be utilized to lower thepressure within said slit whereby a vthread disposed adjacent said slitis drawn in a loop 'into said slit; said slit being of a width toreadily admit said loopV while preventing said loop from twisting; saidshaft having enlarged channels formed around the periphery of andcommunicating with said thread-receiving slit whereby suction pull isstronger in the channels thereby maintaining said thread in a U-shapedloop; means disposed to control air ilow through said suction aperture;a second aperture formed in said shaft communicating with saidthread-receiving slit intermediate the opening of said slit from saidshaft and said suction aperture; and means controlling air ilow throughsaid second aperture.

References Cited in the tile of this patent UNTTED STATES PATENTS1,963,098 Pool lune 19, 1934 2,089,620 Rossmann Aug. 10, 1937 FOREIGNPATENTS 1,242,687 France Aug. 22, 1960 30,514 Switzerland Nov. 16, 1955

1. A DEVICE FOR TEMPORARILY COLLECTING A THREAD WHILE PREVENTINGENTANGLEMENT THEREOF COMPRISING A SHAFT HAVING FORMED THEREIN ALONGITUDINALLY EXTENDING THREAD RECEIVING SLIT; SAID SHAFT ALSO HAVINGFORMED THEREIN A SUCTION APERTURE ADAPTED TO BE UTILIZED TO LOWER THEPRESSURE WITHIN SAID SLIT WHEREBY A THREAD DISPOSED ADJACENT SAID SLITIS DRAWN IN A LOOP INTO SAID SLIT; SAID SLIT BEING OF A WIDTH TO READILYADMIT SAID LOOP WHILE PREVENTING SAID LOOP FROM TWISTING; FIRST MEANSDISPOSED TO CONTROL AIR FLOW THROUGH SAID SUCTION APERTURE; A SECONDAPERTURE FORMED IN SAID SHAFT COMMUNICATING WITH SAID THREADRECEIVINGSLIT INTERMEDIATE THE OPENING OF SAID SLIT FROM SAID SHAFT AND SAIDSUCTION APERTURE; AND SECOND MEANS CONTROLLING AIR FLOW THROUGH SAIDSECOND APERTURE.